Many homeowners have security lights mounted on or near their home. Some of these lights are designed to turn on automatically if a motion detector is triggered and the ambient light level is low. These lights are a deterrent to burglary. Unfortunately, they can be easily defeated if the lamps are unscrewed or loosened either prior to the burglary or during the attempt.
In addition, if the lights are loosened by natural forces, such as vibrations from passing heavy trucks, etc., abrupt jarring motions, such as foundation loosening, machinery movement, sound, repetitive motions etc., then the lamps will also be loosened. Moreover, a loosened lamp would not be noticed during daylight hours.
Various attempts have been made to provide lamp failure devices. U.S. Pat. No. 5,099,177 of Taniguchi discloses a lamp circuit with disconnected lamp detecting device. U.S. Pat. No. 4,980,672 of Murphy discloses an overhead socket smoke detector with theft alarm.
U.S. Pat. Nos. 4,396,868 and 5,168,198 of Watanabe discloses a lamp circuit with disconnected lamp detecting device and a lamplight failure detection system respectively. U.S. Pat. No. 5,359,325 of Ford discloses an automatic monitoring system for airfield lighting systems.
Furthermore, U.S. Pat. No. 5,387,909 of Neel discloses a lamp sensing system for traffic light. In addition, U.S. Pat. No. 5,034,659 of Taniguchi describes a lamp circuit with a disconnected lamp detecting device. U.S. Pat. No. 4,700,126 of Hill shows a vehicular lamp circuit tester.
Moreover, U.S. Pat. No. 4,438,421 of Toyomura discloses an electronic device having a warning means and U.S. Pat. No. 4,295,079 of Otsuka describes a lamp circuit with a disconnected lamp detecting device. U.S. Pat. No. 4,422,068 of Helft discloses an intrusion alarm system for preventing actual confrontation with an intruder.
In addition, U.S. Pat. No. 3,975,627 of Huber shows a burglar-proof guard for light bulbs and U.S. Pat. No. 4,936,789 of Ugalde shows a method and apparatus for preventing the theft of a fluorescent lamp and ballast transformer.
Among other prior art includes U.S. Pat. No. 4,812,827 of Scripps which describes a detector and light assembly and U.S. Pat. No. 5,406,129 of Gilmartin which describes a flashing locator switch control with built-in lamp operation test.
Other prior art includes U.S. Pat. No. 3,382,494 of Mahacsek which describes a theft alarm for an electrical device; U.S. Pat. No. 4,021,679 of Bolle et al., which describes a method and apparatus for automatic switching; U.S. Pat. No. 4,369,435 of Adachi et al., which describes a fire detector and fire alarm system having circuitry to detect removal of one or more detectors at a signal station; U.S. Pat. No. 5,155,474 of Park et al., which describes a photographic security system; U.S. Pat. No. 5,160,000 of Agha et al., which describes an attache and umbrella carrying case; U.S. Pat. No. 5,172,098 of Leyden et al., which describes an alarm system sensing and triggering apparatus; U.S. Pat. No. 5,266,920 of Langner which describes a magnet for use on a refrigerator or the like; U.S. Pat. No. 5,293,115 of Swanson which describes a method and system for sensing removal of a utility meter from its socket; and U.S. Pat. No. 5,434,558 of Zeder which describes an annunciator apparatus for monitoring electrical connections.
U.S. Pat. No. 4,945,341 of Buttimer teaches a current detector for preventing theft.
However, as opposed to the present invention, Buttimer does not describe the detection of the absence or cessation of a magnetic field induced from the current through an electrical load device.
In contrast, the real invention of Buttimer is the capacitance coupling to a power cord which detects when the cord is unplugged from the wall outlet whether the load is in operation or not.
Furthermore, Buttimer makes no use of magnetic fields induced by load currents. Buttimer does not have an alarm communicating with an alarm logic, with the alarm logic turning on the alarm if current drawn is not commensurate with a predetermined load current of the affected lamp, while the load is operational. In contrast, all Buttimer does is use a capacitance coupling to determine if power is shut off due to a plug being removed from a socket and the load is not operational.
While the prior art teaches a variety of methods for failed lamp detection and even an alarm for detecting removal of a smoke detector from a socket, the applications are very specialized.
In contrast to the prior art, the present invention sets off an audible or silent alarm when an ordinary bulb or flood lamp is loosened or removed from the socket of a single or multi-lamp security light fixture, as determined by a loss of current. Furthermore, the alarm remains on or otherwise indicates that an incident had occurred even if the lamp is immediately retightened in its socket. This action is achieved using inexpensive switch elements and electronic subsystems consistent with the product cost limitations dictated by this consumer market.
In other embodiments, the present invention allows the alarm to be set off even before a bulb is removed from a socket, while still lit. The present invention can also detect removal of a lamp by detecting changes in current in the lamp socket.